Incremental Migration

Intel® DPC++ Compatibility Tool Developer Guide and Reference

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ID 768918

Date 3/22/2024

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Incremental Migration

Intel® DPC++ Compatibility Tool provides incremental migration, which automatically merges the results from multiple migrations into a single migrated project.

Incremental migration can be used to

migrate a CUDA* project incrementally, for example 10 files at a time
migrate new CUDA files into an already migrated project
migrate multiple code paths

Incremental migration is enabled by default. Disable incremental migration using the --no-incremental-migration option.

Example 1: Migrate a File with Conditional Compilation Code

This example shows incremental migration for a file sample1.cu that contains conditional compilation code. Content of sample1.cu:

  #ifndef MACRO_A
  ... code path 1 ...
  #elif MACRO_A == 1
  ... code path 2 ...
  #else
  ... code path 3 ...
  #endif

Use the following steps to incrementally migrate sample1.cu.

Generate sample1.dp.cpp, which contains migrated code for code path 1. From the same working directory as the file, run:
```
dpct sample1.cu --out-root=out
```
Generate sample1.dp.cpp, which contains migrated code for code path 1 and code path 2:
```
dpct sample1.cu --out-root=out --extra-arg=”-DMACRO_A=1”
```
Generate sample1.dp.cpp, which contains migrated code for code path 1, code path 2, and code path 3:
```
dpct sample1.cu --out-root=out --extra-arg=”-DMACRO_A=2”
```

The result contains migrated code for each code path.

Example 2: Migrate a Header File Used by Multiple Source Files

This example shows the use of incremental migration for a header file that is included in several source files, each with a different macro definition.

Content of header file sample_inc.h:

  #ifdef MACRO_A
  ... code path 1...
  #else
  ... code path 2...
  #endif

Content of source file sample2.cu:

  #define MACRO_A
  #include "sample_inc.h"
  #undef MACRO_A

Content of source file sample3.cu:

#include "sample_inc.h"

Use the following steps to incrementally migrate the files.

Generate sample2.dp.cpp and sample_inc.h, which contains migrated code for code path 1.

From the same working directory as the file, run:
```
dpct sample2.cu --out-root=out
```
Generate sample3.dp.cpp and sample_inc.h, which contains migrated code for code path 1 and code path 2:
```
dpct sample3.cu --out-root=out
```

The result contains migrated code for each code path.

Limitations

Incremental migration will not be triggered in the following conditions:

Intel® DPC++ Compatibility Tool option --no-incremental-migration is specified.
Different versions of Intel® DPC++ Compatibility Tool are used across multiple migration invocations.
Different options of Intel® DPC++ Compatibility Tool are used across multiple migration invocations. If Intel® DPC++ Compatibility Tool detects that a previous migration used a different option-set, Intel® DPC++ Compatibility Tool will stop migration and exit.

The following options direct Intel® DPC++ Compatibility Tool to generate different migrated code and may break incremental migration. Use the same values for these options across migration invocations to keep incremental migration working.

--always-use-async-handler
--assume-nd-range-dim
--comments
--custom-helper-name
--enable-ctad
--keep-original-code
--no-cl-namespace-inline
--no-dpcpp-extensions
--no-dry-pattern
--optimize-migration
-p
--process-all
--sycl-named-lambda
--use-experimental-features
--use-explicit-namespace
--usm-level
--vcxprojfile

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Intel® DPC++ Compatibility Tool Developer Guide and Reference

Incremental Migration

Example 1: Migrate a File with Conditional Compilation Code

Example 2: Migrate a Header File Used by Multiple Source Files

Limitations